This invention relates to the art of scrap metal conveyors of the type having an elongated trough in which a pusher assembly is supported for longitudinal reciprocation to advance scrap metal along the trough and, more particularly, to an improved pusher assembly for such a conveyor.
Scrap metal conveyors of the character having an elongate trough supporting a longitudinally reciprocable pusher assembly for conveying metal filings, turnings, and the like along the trough in the direction from one end thereof to the other are well known in the art. Generally, the pusher assembly in such a conveyor is comprised of a longitudinally extending push rod adapted to be reciprocated such as by a double acting hydraulic piston and cylinder unit at one end of the trough, and a plurality of pusher elements often referred to as plows axially spaced apart along the push rod and rigidly fastened thereto for displacement therewith. Often, the push rod is in the form of a longitudinally split tube, or an inverted V-shaped angle member, supported for longitudinal reciprocation and lateral guidance by a longitudinally extending support and guide assembly on the bottom wall of the trough. Examples of such previous arrangements are illustrated in U.S. Pat. Nos. 3,659,702 to Assauer and 3,777,880 to Becker et al which illustrate a split tube type push rod slidably supported on a circular support member disposed within the split tube, and U.S. Pat. Nos. 3,112,025 to Peras and 3,802,552 to Gann et al which illustrate inverted V-shaped push rods supported on underlying rollers and bearing plates, respectively. In other previous arrangements, such as those disclosed in U.S. Pat. Nos. 3,797,637 to Wissmann and 4,082,178 to VanNocker, the pusher elements or plows slidably engage a wear plate provided on the bottom wall of the trough.
In all of the pusher assemblies heretofore provided for scrap metal conveyors of the foregoing character, including those pusher assemblies specifically mentioned above, the pusher elements or plows are rigidly attached to the push rod member, or to an axially coupled assembly of push rod members, against displacement circumferentially of and relative to the push rod axis. This rigid relationship presents a number of problems in connection with the manufacture, maintenance and use of the pusher assembly and the conveyor apparatus. In this respect, the trough and pusher assembly may be fifty to one-hundred feet in length, and each may be comprised of axially coupled sections of ten feet, for example. It is extremely difficult to obtain and maintain alignment of the trough or trough sections, alignment of the support and guide components for the pusher assembly, and alignment of the pusher or plow elements relative to one another along a length of push rod. Warping of the trough circumferentially along the length thereof is not at all uncommon, and corresponding warpage of the support and guide arrangement accompanys such trough warpage. Such trough warpage and/or pusher element misalignment results in undesirable wearing interengagement between the component parts of the pusher assembly, the support and guide components therefor, and/or the conveyor's trough, and can result in the application of torsional forces on the push rod as a result of the latter being constrained to follow a circumferentially distorted path of reciprocating movement. Such torsional forces, in addition to causing undesirable wearing interengagement between the components of the pusher assembly and the support and guide components therefor, can transmit such torsional forces to the mechanism by which the pusher assembly is reciprocated. While such torsional forces may not be of considerable magnitude, the repeated imposition of such forces on the component parts reduces the life thereof and results in undesirable maintenance and replacement costs.
Additionally, with respect to those pusher assembly support arrangements wherein the push rod is supported on a circular support member or on bearing plates, a very small contact area exists between the push rod and the support components therefor, and this contact area cannot be easily lubricated. This, together with the weight of the pusher assembly results in rapid wear of both the push rod and the support component and thus an undesirably high replacement requirement. Further in connection with previous pusher assemblies and the periodically required maintenance and/or replacement of component parts thereof, the pusher elements or plows are generally welded or otherwise secured to a push rod section which may, for example, be ten feet long and carry five pusher elements or plows. If one such pusher element breaks or otherwise requires maintenance and/or replacement, maintenance without removal of the push rod section requires working on the element within the trough. This is not only inconvenient but can also be hazardous if welding is required and a flammable lubricant exists in the trough. If such inconvenience and/or danger is to be avoided, the damaged section of the pusher assembly must be removed from the trough. Such removal in connection with the pusher assemblies disclosed in the patents referred to hereinabove requires either sliding of the pusher assembly along the support and guide components and outwardly of the discharge end of the trough to achieve removal of the damaged section of the pusher assembly, or the separation of pusher assembly portions at the axially opposite ends of the damaged portion to achieve elevation and removal of the latter from the trough. In any event, such a removal procedure is time consuming and difficult. Even in such prior art arrangements such as those illustrated in U.S. Pat. Nos. 3,158,257 to Peras and 3,175,677 to Peras wherein adjacent short sections of the push rod assembly are pivotally coupled together, the pivotal coupling element is either not removable or, upon removal, does not enable elevation of the pusher element from the support and guide components, whereby either an elongated section of the push rod assembly must be removed from the trough, or the pusher elements must be removed from the end of the trough by sliding the elements along the support and guide components.
With regard to replacement requirements in connection with previously available pusher assemblies, if a pusher element or other component part on an elongate section of a push rod assembly is damaged beyond repair, replacement of an entire length of the push rod assembly is required. Such a pusher assembly having an unrepairable pusher element is most often totally lost in that the pusher element cannot be easily removed and reused. This is not only expensive, but requires the user to stock such elongate push rod sections. Still further, in those previous designs wherein the pusher elements or plows are welded on an elongate length of pusher bar, the pusher bar acts as a heat sink during the welding process causing excessive heat to be used. The pusher elements are often made of cast iron, and such heating during welding weakens the weld joint to the extent that the pusher element is easily broken loose therefrom, thus promoting maintenance and replacement requirements.